The torso a b in its thinnest part measures a foot; and from a to b is 2 feet, which makes two squares to the seat—its thinnest part goes 3 times into the length, thus making 3 squares.
[Footnote: See Pl, VII, No. 2, the lower sketch.]
Taken from The Notebooks of Leonardo da Vinci edited by Jean Paul Richter, 1880.